As a polyglot and a former translator, I am a huge advocate for software localization, which also means testing software in multiple languages. Code that works flawlessly in English can totally break down in another language — whether it’s due to missing translations, translations that don’t fit into the space provided by the UI, or bugs that only pop up in other languages. (I found examples of all three while testing the WordPress apps today.)
But that’s not the only reason I like testing in other languages. As soon as I switch to one of my non-native languages, I’m forced to slow down and take a fresh look at the interface. Is everything where I expect it to be? Am I seeing what I’m supposed to see on this screen? Do all the buttons work the way they should? Working in another language can help you look at the software with a fresh set of eyes and find bugs that occur across languages — even in English.
Give it a try! Pick another language you speak — or one you’re trying to learn — and use it while you test. I’m trying to spend at least one day a month using WordPress.com and the WordPress apps in another language. It’ll help my testing, and I’m sure it’ll also help my language skills. :)